Resonant device for musical instruments



Margh 24, 1925.

. 1,530,984 H. O. CRIPPEN RESONANT DEVICE FOR MUSICAL INSTRUMENTS Filed March 6, 1922 2 Sheets-Sheet 1 7'. J/erberf O. Gv b oen @JMQJV March 24, 1925. 1,530,984

H. O. CRIPPEN RESONANT DEVICE FOR MUSICAL INSTRUMENTS gfif, 6 Filed March 6, 1922 2 Sheets-$heet 2 i I 1 6 a? i 4 l i Ir /0 Patented Mar. 24, 1925.

UNITED STATES Y HERBERT O. CRIPPEN,

or CHICAGO, ILLINOIS.

RESONANT DEVICE FOR MUSICAL INSTRUMENTS.

Application filed March 6, 1922. Serial No. 541,446.

To all whom it may concern:

Be it known that I, HERBERT O. CRIPPEN, a citizen of the UnitedStates, residing .at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Resonant Devices for Musical Instruments, of which the following is a specification.

This invention relates to resonant devices for musical instruments.

The device is especially adaptable for use with pianos and is attachable to the sound board of any type of pianos.

The device provides an air-tight resonant.

casing enclosing a chamber, one of the walls of the casing being parallel with the sound board and tensioned by means bearing on the sound board.

One of the objects of the invention is the provision of means for increasing the resonance, volume, tones and other desirable qualities of pianos.

A further object is to provide an improved air chamber within the casing which is separably attached to the back of the sound board, the parallel wall of which 'is under tension and bounding wall secured directly to the board.

A further object is to rearrange the construction of pianos to accommodate my resonant attachment.

Another object is to provide a resonant air chamber, containing dead air, that is air that is not in circulation, and open thru the sound board, the area of the casing being somewhat in proportion to the number of tensioned strings superimposed above the sound board.

Other objects and advantages of the in vention will hereinafter appear from a consideration of the following description when taken in conjunction with the drawings, wherein Fig. 1 is a top plan View of a grand piano showing the strings, and the improved device in broken lines therebelow.

Fig. 2 is a bottom plan view showing the sound board and the improved sound amplifying device attached thereto.

Fig. 3 is a section taken on'line 3-3 of Fig. 1.

Fig. 4 is a substitute metal frame for the grand piano, to take the place of the wooden frame usually employed to withstand the strain imposed upon the structure.

Fig. 5 is a rear view of an upright piano.

the sound board 12.

Fig. 6 is .a perspective view of the casing enclosing the amplifying chamber before the casing is secured to :the sound board.

In all the views the same reference characters are employed, to indicate similar parts.

In the drawings 10 is the outside casing of a piano in which is located the string plate 11 and underlying the string plate is The sound board usuall-y is provided with a series of strengthening ribs 13. The main frame of the piano consists usually of the sills 14 and 15 spaced apart and supported by the studs 16 and 17.

Between these studs there are other studs.

of same character usually consisting of maple or other hard wood similar to the studs 16 and 17, located intermediate of these studs to withstand the strain imposed upon the frame of the piano.

To take the place of the intermediate studs I provide two iron frames 18 and 19 much thinner than the studs 16 and 17 to secure room between the supporting frame and the sound board 12 for the casing 20. The casing 20, containing the air chamber, to be attached to the back of the sound board is located in the space permitted by the use of the iron frames 18 and 19, and consist of the wooden structure 20 having a wall 21, parallel with the sound board, and having a wall 22 the edges of which are connected or glued directly to the rear surface of the iound board, as more clearly shown in The chamber in the casing. 20 contains dead air at normal atmospheric pressure, the chamber being vented thru the sound board by the holes or apertures 23. Posts 241 bear against the wall 21, of the casing 20, and also against the confronting surface of the sound board 12 to give some tension to the outer wall 21 of the casing 20, so as to render the device more sensitive.

In placing the casing 20 in contact with the sound board 12 it may be necessary to remove some of the ribs 13, as more clearly shown in Fig. 5, the casing securely fastened to the sound board which serves in lieu of the ribs may be placed inside of the casing, if desired. The object is to provide a casing secured directly to the rear surface of the sound board and to contain a chamber in which air at atmospheric pressure is entrapped.

One of the essential features of the invenconnected to one of the surfaces of the sound o board, and vibrates bodily with the sound board and in its effect contributeslargely to the tone, volume and-other desirable qualities ofsound produced by the piano.

While I have herein described, a single embodiment for the purpose of'clear disclosure, it will be manifest to persons skilled in the art that many changes may be made in the general arrangement and configuration of the parts within the scope'of the appended claim. I I a I Having described my invention what I Patent is In combination with a musical instrument having a fiat ribbed sound board with claim as new and desire to secure by Letters strings on its front face, a resonant casing 25 rectly connected to said rear face of the sound board, said casing being wholly and directly supported by the sound board" and bodily movable therewith and out of contact with the ribs of the board.

1 In testimony whereof I hereunto, subscribed my name.

- HERBERT O. CRIPPEN. 

